This application is based on and claims priority to Japanese Patent Application No. 2000-236816, filed Aug. 4, 2000.
The present invention generally relates to engine control systems. More particularly, the present invention relates engine control systems arranged to detect and respond to engine overheat conditions.
As is well known, engines powered by internal combustion engines that are mounted inboard of the hull and within an engine compartment generally require adequate cooling through a water cooling system. It is desirable to ensure that adequate cooling water can reach the engine and the associated exhaust system to reduce the temperature of these components. Due to the construction of most personal watercraft, which is discussed below, the exhaust cooling system often can fail or have reduced efficacy without the rider becoming aware of the condition until the engine seizes or the catalyst is damaged.
Personal watercraft are a relatively small type of watercraft wherein the rider sits more upon than in the watercraft. With this type of watercraft, the engine compartment is frequently formed below the rider""s area or immediately forwardly of it. In addition, both the engine and the exhaust system associated with the engine are generally encased within the engine compartment.
To provide an indication of an operational state of the cooling system, a telltale line is often connected to the cooling system. The telltale line emits a constant trickle of water so long as water is flowing through the cooling system. If the water from the tell-tale line stops flowing, then the rider has a visual confirmation of a problem within the cooling system; however, such an indication often is not early enough to allow the operator time to return to port. In addition, the absence of the water trickle may not attract the attention of the operator until it is too late. Moreover, even should such an indication become apparent to the operator, the operator may not operate the engine at a slow enough speed to avoid damaging various engine and exhaust system components.
Accordingly, an engine temperature control system is desired that will positively alert the operator to a malfunction within the cooling system and that will act to reduce the temperature of the engine and exhaust system. For instance, once a high temperature operating condition is detected, the engine could be slowed through misfiring and eventually stalled to compensate for the malfunction. Importantly, the system should be able to detect if the sensors used to identify the malfunction are operational or not. In addition, the system should not allow an engine restart after the engine is stopped due to the high temperature condition until the operator positively recognizes that a problem exists. Therefore, it is desired to provide an improved engine temperature control system for a personal watercraft having one or all of these functions, aspects or advantages.
Accordingly, one aspect of the present invention involves an exhaust temperature control system for an engine having an exhaust system that is cooled by an exhaust cooling system. The control system comprises a coolant sensor that is adapted to sense an operational condition of the exhaust cooling system. A controller is electrically connected to the coolant temperature sensor and the controller receives an input signal from the coolant temperature sensor, which signal is indicative of an operating condition of the exhaust cooling system. The controller also is controllably connected to a switchable relay. The relay is adapted to interrupt a power supply to a starter motor with the controller interrupting the power supply to the starter motor when the input signal indicates a malfunction in the exhaust cooling system.
Another aspect of the present invention involves a method of alerting an operator of a water vehicle to a malfunction in an exhaust cooling system. The method comprises sensing a temperature of an exhaust system and comparing the sensed temperature to a preset temperature. The method also involves activating an alarm if the sensed temperature is less than the preset temperature.
A further aspect of the present invention involves a method of alerting an operator of a water vehicle to a malfunction in an exhaust cooling system. The method comprises sensing a coolant temperature of an exhaust cooling system before ignition of an engine, comparing the sensed temperature to a first preset temperature and activating an alarm if the sensed temperature is more than the first preset temperature.